[chiphead]

I took a good look at the thrust inserts for my 3" main stroker build. I noticed something strange on one half shell. Looks like the brass was buffed away or something right at the edge. These are new 4040M1 from Summit.
Is this a problem or not?

[Cliff R]

Run them, see it all the time.

When you add the oil grooves to the thrust surface (good idea IMHO) do a "tear drop" wide at the bearing line then tapering down right up to the outer edge but not all the way to it to keep the oil "trapped" and supplying full pressure to the thrust surface without a leak path.......Cliff

[tempest1964]

Cliff, for us guys that haven’t done this before. Could you be a little more specific as to number of grooves and maybe a picture of said groove. Sometimes a picture helps me more than a written description.
Thanks
Tony

[chiphead]

Pictures are a good idea. I've read here about modifying the thrust main so that pressurized oil is fed to the rear thrust surface. Pics would really clarify what needs to be done.

[Cliff R]

I'll have to dig around to find some and post pics later.

I put the grooves at 10 and 2 oclock as you have done but use a round file and form a "tear drop" shape deeper toward the bearing line then tapering to a round point and not quite reaching the outer edge.

Doing this will pressurize the groove and no leak path. Probably doesn't make a darned bit of difference, but that is how is it often found on main thrust bearings for other makes, so basically copying that deal.

I've done this on all my engines and to date haven't had any issues whatsoever in that area.

Another thing I do (often considered "overkill") is to drill one of the front main oil gallery plugs with a .030" hole to spray the timing set. GM started doing that on later production SBC engines, can't remember when I saw the first one done that way, probably in the 1980's, but I've been doing that to all my engines here as well.......Cliff

[64-3Deuces]

Pic of thrust bearing with oil grooves in the flange. Yep, it's a chebby but same principle applies. Been a while since I worked on the Poncho engine bottom end but IIRC the replacement thrust bearing already had the oil grooves.

No problem with the items you noted at the parting line. From Clevite tech info: "...Thrust bearings typically consist of two flat mating surfaces with no natural wedge shape in the clearance space to promote the formation of an oil film to support the load... Either tear-drop or through grooves on the flange faces and wedge shaped ramps at each parting line allow oil to enter between the shaft and bearing surfaces..."

[tempest1964]

Good stuff-thanks!

[Torquewar]

Yes thanks for the pic. and explanation.

[Schurkey]

Originally Posted by Cliff R

Another thing I do (often considered "overkill") is to drill one of the front main oil gallery plugs with a .030" hole to spray the timing set. GM started doing that on later production SBC engines, can't remember when I saw the first one done that way, probably in the 1980's, but I've been doing that to all my engines here as well.......Cliff

First Guess: This has nothing to do with lubing the timing set. The hole is to purge air from the oil gallery at startup, spraying onto the timing set is entirely incidental and unimportant.

[Cliff R]

Yes, it will accomplish both things and I don't think it is possible to over-lubricate a timing set. Oil is also used to cool parts in addition to lubricating them, so another side benefit. Certainly no negatives from that modification or the thrust bearing one either, at least that I know of.......Cliff

["QUICK-SILVER"]

Originally Posted by Cliff R

Another thing I do (often considered "overkill") is to drill one of the front main oil gallery plugs with a .030" hole to spray the timing set. GM started doing that on later production SBC engines, can't remember when I saw the first one done that way, probably in the 1980's, but I've been doing that to all my engines here as well.......Cliff

First time I saw that was in the directions that came with a true roller timing chain set.
Pretty sure it said waranty was void without it.

Clay

[Cliff R]

I don't use the "true roller" chains on my own engines. Got talked into one once and it did a fine job for several years. At the time I was street driving and racing the car couple of times a week. So not only logging a LOT of street miles, it was getting "flogged" pretty good at the track as well.

I was also doing a lot of testing at that time, and had the front cover off many times moving the cam around with the 9 degree keyway feature.

The chain stayed pretty tight initially, but at the end of it's life cycle it just for some unknown reason stretched out so far it KILLED the engine power and the car slowed WAY down at the track. I replaced the chain only and freshened up the engine.

I went back to the good 3/4" wide link plate sets for my current 455 and it has been flawless now since 2009, timing hasn't budged and I've had the front cover off 3 times and the chain is fine. Has a little slack in it, which is normal for link plate set after "run-in". The only thing I don't like about the factory sets is having to use off-set keys to move the cam around, and they are getting harder to obtain in recent years since Mopar discontinued their multiple off-set key "set". I bought all the ones that have came up on Ebay so good to go for a while yet........Cliff

[Formulas]

My 350 i assembled last year i drilled the front drivers galley plug when i primed the oil system i could see through the fuel pump hole in the front cover the oil was cascading down to the timing gear / chain teeth as the mesh on the crankshaft so during running large amounts of oil are being forced through the chain links,

[Blued and Painted]

If you count the drilled plug at rear of right oil galley, there are 50 points to purge air. Drilling the front plug for air purge would be redundant.
Drilling the front plug for lubrication would be engineering. JMO.

[chiphead]

Is it necessary to do any other mods to the thrust main? I did a search, and other threads mention:

Drilling the oil hole in the main bearing out to match the block feed passage
Filing a small V at the parting line to channel oil to rear thrust face
Deburring the parting lines

[Schurkey]

Originally Posted by chiphead

Drilling the oil hole in the main bearing out to match the block feed passage

Is this a SIZE issue, or a LOCATION issue?

Most of the time, I see that the oil hole in the block doesn't align with the hole in the bearing. Some engine families are REALLY BAD for this.

"I" would rather oblong the hole in the block to match the hole in the bearing, than to drill/grind the bearing to match the hole in the block. The hole in the bearing is perfectly adequate to supply oil to the journal, but the alignment is faulty. Correcting the alignment is all that's needed.

[Cliff R]

Is it necessary to do any other mods to the thrust main?

Check for fit in the block and caps, rare to see an issue there. Make sure to pry the crank back and forth and hold forward pressure on the crank when torqueing down the main bearing cap. This will line up the thrust surface on both halves equally.

Then check end play, hopefully it's down around .004-.006".

I would and install the bottom timing gear and balancer without driving them in place. If they are showing some interference fit resist the urge to drive them in place while the crank is against the thrust bearing. Never a good idea to beat on the bearing from either end once everything is in place and torqued to spec......Cliff

["QUICK-SILVER"]

Originally Posted by chiphead

Is it necessary to do any other mods to the thrust main? I did a search, and other threads mention:

Drilling the oil hole in the main bearing out to match the block feed passage
Filing a small V at the parting line to channel oil to rear thrust face
Deburring the parting lines

Do these bearings have a hole or slot for oil feed in the groove?
AND
Summit says 1/2 groove but the pics look like 3/4 groove...
https://www.summitracing.com/parts/slp-4040m1

If you're going to flog this thing hard, I'ld take every step possible to keep ample oil going to the rod bearings.

Clay

[chiphead]

Both the 113M and 4040M have a slot for the oil feed. I'm not sure if the slot is the same, I'll have to compare the two. Both are also 3/4" groove, the upper is fully grooved and the lower has grooves partway down.

One mod I did to the block was to grind back the sharp edges in the oil galley drilled passages and smooth them with a debur cone in a dremel. On #1, its amazing how much the sharp edges could reduce flow to the opposite side lifter galley.

[beertracker]

While trying to find a photo that describes the thrust bearing mod I found the following. Does the following photos and write up describe the thrust bearing mod in this thread? As previously stated photos showing the mod are needed to convey information accurately.

http://www.spottsperformance.com/IA2block/IA2seven.jpg
https://st.hotrod.com/uploads/sites/...t_bearings.jpg
https://www.dsmtuners.com/threads/th...ention.345564/

Attached is the Sealed Power 151M10 thrust bearing I am using. It already has 3 oil grooves per side. Based on the mod should I add two more grooves at 10:00 and 2:00 positions?